1. Field of the Invention
This invention relates, in general, to pedestals for tracking antenna and more particularly to satellite tracking antenna pedestals used on ships and other mobile applications and methods for their use.
2. Description of Related Art
The invention is especially suitable for use aboard ship wherein an antenna is operated to track a transmitting station, such as a communications satellite, notwithstanding roll, pitch, yaw, and turn motions of a ship at sea.
Antennas used in shipboard satellite communication terminals typically are highly directive. For such antennas to operate effectively they must be pointed continuously and accurately in the direction toward the satellite.
When a ship changes its geographical position, or when the satellite changes its position in orbit, and when the ship rolls, pitches, yaws and turns, an antenna mounted on the ship will tend to become misdirected. In addition to these disturbances the antenna will be subjected to other environmental stresses such as vibrations caused by shipboard machinery and shocks caused by wave pounding. All of these effects must be compensated for so that the antenna pointing can be accurately directed and maintained in such direction.
Compactness in size and lightness in weight are of paramount importance for antenna pedestals used on ships. Small ships and boats which operate in rough seas routinely experience roll amplitudes of +/−35 degrees or more, pitch amplitudes of +/−15 degrees, and repetitive wave pounding shocks of 2 g's. Antenna pedestals which are compact and light yet rugged are highly desired.
An exemplar of the prior art is U.S. Pat. No. 5,419,521 to Matthews which shows a three-axis pedestal. While the disclosed pedestal is quite effective, additional stabilization may be necessary, for example, during extremely rough seas and gale force winds, and additional serviceability would be advantageous.
In particular, modern edge mast-mounted satellite antennas demand isolation from vibration and shock generated by ship for better pointing accuracy and long structural life. Moreover, given the demanding environments of operation, modern edge mast-mounted satellite antennas would benefit from improved designs which facilitate at-site maintenance and repair.
It would therefore be useful to provide an improved pedestal for a tracking antenna having vertical and horizontal vibration isolation and readily accessible components to overcome the above and other disadvantages of known pedestals.